CMOS有源集成像素传感器检测高能物理粒子

研究适用于下一代国际线性电子对撞机中顶点探测器的CMOS有源集成像素传感器.实验芯片现采用标准0.35μmCMOS工艺设计,像素矩阵为128行×32列,像素大小为25μm×25μm,在像素内部实现相关双次采样技术.通过采用放射源55Fe测定,芯片等效输入随机噪声为12个电子,而固定噪声为3个电子.传感器的电荷-电压转换系数达59μV/e-.在170MHz工作主频下,芯片信号处理速度达12μs/帧.芯片模拟部分功耗小于30mW.

基于CMOS集成有源传感器的新型高能物理粒子轨迹追踪器

本文研究了一个采用标准0.35μm CMOS工艺制造的新型高能物理粒子轨迹追踪器.这个新型的追踪器运用CMOS有源像素传感器技术(CMOS Monolithic Active Pixel Sensors,MAPS)将信号的探测与处理电路集成在一起,在像素的内部实现了相关双次采样操作(Correlated Doubled Sampling,CDS).实验芯片包含一个128行×32列的像素矩阵,其中,像素的大小为25×25μm2.通过采用放射源55Fe的测定,得到像素的等效输入随机噪声(Temporal Noise)仅为12个电子而固定噪声(Fixed Pattern Noise,FPN)仅为4个电子.传感器的电荷-电压转换系数(Charge-to-Voltageconversion Factor,CVF)为60μV/e-.测试中,芯片的信号读取速度达到了12μs/帧.

中国极化电子离子对撞机计划

轻子散射实验是探索核子与原子核结构的理想工具。中国电子离子对撞机(Electron Ion Collider in China,EicC)建议书设想在已开建的强流重离子加速器装置(High Intensity heavy ion Accelerator Facility,HIAF)的基础上,升级质子束流为20 GeV的极化束流,并建造2.8~5 GeV极化电子束流,从而实现质心系能量为15~20 GeV的双极化电子-离子对撞。EicC设计的亮度为(2~4)×10^33cm^-2·s^-1,质子束流极化率达到70%,电子束流极化率达到80%。该装置除了能提供极化轻离子束流(例如:氦-3)外,也可产生非极化重离子束流(碳-12~铀-238)。EicC将聚焦核子海夸克部分子结构、原子核物质结构与性质、奇特强子态三个方面的物理研究。高亮度、高精度的对撞机有助于精确地测量核子结构函数并对核子进行三维成像,揭示强相互作用的动力学规律;原子核部分子分布包括核子短程关联以及原子核介质效应同样是该提案的重要科学目标;EicC能区接近重味夸克产生阈值,在研究重味强子谱方面拥有低背景的独特优势,有助于发现研究新的奇特强子态。质子质量起源问题也可以通过重味矢量介子的产生来研究。为了完成上述物理目标,我们将利用最先进的探测器技术建造接近全立体角覆盖的EicC对撞机谱仪。在准备EicC白皮书的过程中,我们得到世界各国专家的支持。EicC的物理与已有的实验和美国即将建设的EIC中的物理项目相互补充。EicC的建成及运行有望引领前沿的中高能核物理研究,使我国在加速器和探测器先进技术等领域实现跨越式发展,为我国核物理与强子物理以及相关科学领域提供大型综合实验平台与人才培养基地。

中法天文卫星(SVOM)伽玛暴联合探测任务

中法天文卫星SVOM是中法两国合作的伽玛暴探测任务,由中国国家航天局(CNSA)和法国国家空间研究中心(CNES)批准立项,中国科学院负责总体研制.SVOM是继美国SWIFT任务之后最重要的伽玛暴多波段探测项目,是一颗功能强大的天文卫星,具有多波段观测、快速机动、灵活操作及地面后随观测能力.SVOM将开创一个非常广阔的探测领域.本文介绍了项目组织、任务目标、卫星和有效载荷、地面段以及运控概念.

High-frequency structure design and RF stability analysis of a 4-vane radio frequency quadrupole with pi-mode stabilizer loops

Compact accelerator-based neutron source facilities are garnering attention and play an important and expanding role in material and engineering sciences,as well as in neutron science education and training.Neutrons are produced by bombarding a low-energy proton beam onto a beryllium or lithium target.In such an acceleratorbased neutron source,a radio frequency quadrupole(RFQ)is usually utilized to accelerate a high-intensity proton beam to a few MeV.This study mainly covers the highfrequency structure design optimizations of a 4-vane RFQ with pi-mode stabilizer loops(PISLs)and its RF stability analysis.A 176 MHz RFQ accelerator is designed to operate at a 10%duty factor and could accelerate an80 mA proton beam from 65 keV to 2.5 MeV within a length of 5.3 m.The adoption of PISLs ensures high RF stability,eases the operation of the accelerator,and implies less stringent alignment and machining tolerances.

Enhanced ion acceleration using the high-energy petawatt PETAL laser

The high-energy petawatt PETAL laser system was commissioned at CEA’s Laser M´egajoule facility during the 2017–2018 period.This paper reports in detail on the first experimental results obtained at PETAL on energetic particle and photon generation from solid foil targets,with special emphasis on proton acceleration.Despite a moderately relativistic(<1019 W/cm^(2))laser intensity,proton energies as high as 51 MeV have been measured significantly above those expected from preliminary numerical simulations using idealized interaction conditions.Multidimensional hydrodynamic and kinetic simulations,taking into account the actual laser parameters,show the importance of the energetic electron production in the extended low-density preplasma created by the laser pedestal.This hot-electron generation occurs through two main pathways:(i)stimulated backscattering of the incoming laser light,triggering stochastic electron heating in the resulting counterpropagating laser beams;(ii)laser filamentation,leading to local intensifications of the laser field and plasma channeling,both of which tend to boost the electron acceleration.Moreover,owing to the large(∼100μm)waist and picosecond duration of the PETAL beam,the hot electrons can sustain a high electrostatic field at the target rear side for an extended period,thus enabling efficient target normal sheath acceleration of the rear-side protons.The particle distributions predicted by our numerical simulations are consistent with the measurements.

Onboard GRB trigger algorithms of SVOM-GRM

The Gamma-Ray Monitor （GRM） is a high energy detector onboard the future Chinese-French satellite named the Space-based multi-band astronomical Variable Object Monitor which is dedicated to studies of gamma-ray bursts （GRBs）. This paper presents an investigation of the algorithms that look for GRBs by searching for a significant increase in the photon count rate for the computer onboard GRM. The trigger threshold and trigger efficiency, which are based on a given sample of GRBs, are calculated with the algorithms. The trigger characteristics of onboard instruments GRM and ECLAIRs are also analyzed. In addition, the impact of solar flares on GRM is estimated, and a method to distinguish solar flares from GRBs is investigated.

Detecting exoplanets with FAST?

We briefly review the various proposed scenarios that may lead to nonthermal radio emissions from exoplanetary systems(planetary magnetospheres, magnetosphere-ionosphere and magnetospheresatellite coupling, and star-planet interactions), and the physical information that can be drawn from their detection. The latter scenario is especially favorable to the production of radio emission above 70 MHz. We summarize the results of past and recent radio searches, and then discuss FAST characteristics and observation strategy, including synergies. We emphasize the importance of polarization measurements and a high duty-cycle for the very weak targets that radio-exoplanets prove to be.

The mini-GWAC optical follow-up of gravitational wave alerts – results from the O2 campaign and prospects for the upcoming O3 run

The second(O2)observational campaign of gravitational waves(GWs)organized by the LIGO/Virgo Collaborations has led to several breakthroughs such as the detection of GW signals from merger systems involving black holes or neutrons stars.During O2,14 GW alerts were sent to the astronomical community with sky regions mostly covering over hundreds of square degrees.Among them,six were finally confirmed as real astrophysical events.Since 2013,a new set of ground-based robotic telescopes called Ground-based Wide Angle Camera system(GWAC)project and its pathfinder mini-GWAC has been developed to contribute to the various challenges of multi-messenger and time domain astronomy.The GWAC system is built up in the framework of the ground-segment system of the SVOM mission that will be devoted to the study of the multi-wavelength transient sky in the next decade.During O2,only the mini-GWAC telescope network was fully operational.Due to the wide field of view and fast automatic follow-up capabilities of the mini-GWAC telescopes,they were adept to efficiently cover the sky localization areas of GW event candidates.In this paper,we present the mini-GWAC pipeline we have set up to respond to GW alerts and we report our optical follow-up observations of eight GW alerts detected during the O2 run.Our observations provided the largest coverage of the GW localization areas with a short latency made by any optical facility.We found tens of optical transient candidates in our images,but none of those could be securely associated with any confirmed black hole-black hole merger event.Based on this first experience and the near future technical improvements of our network system,we will be more competitive in detecting the optical counterparts from some GW events that will be identified during the upcoming O3 run,especially those emerging from binary neutron star mergers.

Sky reconstruction for the Tianlai cylinder array

We apply our sky map reconstruction method for transit type interferometers to the Tianlai cylin- der array. The method is based on spherical harmonic decomposition, and can be applied to a cylindrical array as well as dish arrays and we can compute the instrument response, synthesized beam, transfer func- tion and noise power spectrum. We consider cylinder arrays with feed spacing larger than half a wavelength and, as expected, we find that the arrays with regular spacing have grating lobes which produce spurious images in the reconstructed maps. We show that this problem can be overcome using arrays with a different feed spacing on each cylinder. We present the reconstructed maps, and study the performance in terms of noise power spectrum, transfer function and beams for both regular and irregular feed spacing configura- tions.

Energy calibration of HPGe detector using the high-energy characteristic γ rays in 13C formed in 6Li + 12C reaction

An 6 Li+89Y experiment was conducted at the Laboratori Nazinali di Legnaro,INFN,Italy.The 550μg/cm^2 thick^89Y target was backed on a 340μg/cm^2 thick 12C foil.The severalγrays in the experiment with energies higher than 3000 keV can most likely be ascribed to the transitions in the 13C nuclei,which can be formed through various interactions between the 6 Li beam and the 12C foil.The high-energy properties ofγrays in 13C are employed for energy calibrating HPGe detectors,especially for the>3000 keV region,which is impossible to reach by common standard sources(152Eu,133Ba,etc.).Furthermore,γ-γand particle-γcoincidence measurements were performed to investigate the formation of 13C.

Solar-stellar astrophysics and dark matter

In this review, we recall how stars contribute to the search for dark matter and the specific role of the Sun. We describe a more complete picture of the solar interior that emerges from neutrino detections, gravity and acoustic mode measurements of the Solar and Heliospheric Observatory （SOHO） satellite, becoming a reference for the most common stars in the Universe. The Sun is a unique star in that we can observe directly the effect of dark matter. The absence of a signature related to Weakly Interacting Massive Particles （WIMPs） in its core disfavors a WIMP mass range below 12 GeV. We give arguments to continue this search on the Sun and other promising cases. We also examine another dark matter candidate, the sterile neutrino, and infer the limitations of the classical structural equations. Open questions on the young Sun, when planets formed, and on its present internal dynamics are finally dis- cussed. Future directions are proposed for the next decade： a better description of the solar core, a generalization to stars coming from seismic missions and a better under- standing of the dynamics of our galaxy which are all crucial keys for understanding dark matter.

On the line profile changes observed during the X2.2 class flare in the active region NOAA 11158

The solar active region NOAA 11158 produced a series of flares during its passage through the solar disk. The first major flare （of class X2.2） of the current solar cycle occurred in this active region on 2011 February 15 around 01：50 UT. We have analyzed the Dopplergrams and magnetograms obtained by the Helioseismic and Magnetic Imager （HMI） instrument onboard Solar Dynamics Observatory to examine the photospheric velocity and magnetic field changes associated with this flare. The HMI instrument provides high-quality Doppler and magnetic maps of the solar disk with 0.5＂ spatial scale at a cadence of 45 s along with imaging spectroscopy. We have identified five locations of velocity transients in the active region during the flare. These transient velocity signals are located in and around the flare ribbons as observed by Hinode in the Ca II H wavelength and the footpoints of hard X-ray enhancement are in the energy range 12-25 keV from RHESSI. The changes in shape and width of two circular polarization states have been observed at the time of transients in three out of five locations. Forward modeling of the line profiles shows that the change in atmospheric parameters such as magnetic field strength, Doppler velocity and source function could explain the observed changes in the line profiles with respect to the pre-flare condition.

Imaging the initial condition of heavy-ion collisions and nuclear structure across the nuclide chart

High-energy nuclear collisions encompass three key stages:the structure of the colliding nuclei,informed by low-energy nuclear physics,the initial condition,leading to the formation of quark-gluon plasma(QGP),and the hydrodynamic expansion and hadronization of the QGP,leading to fnal-state hadron distributions that are observed experimentally.Recent advances in both experimental and theoretical methods have ushered in a precision era of heavy-ion collisions,enabling an increasingly accurate understanding of these stages.However,most approaches involve simultaneously determining both QGP properties and initial conditions from a single collision system,creating complexity due to the coupled contributions of these stages to the fnal-state observables.To avoid this,we propose leveraging established knowledge of low-energy nuclear structures and hydrodynamic observables to independently constrain the QGP's initial condition.By conducting comparative studies of collisions involving isobar-like nuclei—species with similar mass numbers but diferent ground-state geometries—we can disentangle the initial condition's impacts from the QGP properties.This approach not only refnes our understanding of the initial stages of the collisions but also turns high-energy nuclear experiments into a precision tool for imaging nuclear structures,ofering insights that complement traditional low-energy approaches.Opportunities for carrying out such comparative experiments at the Large Hadron Collider and other facilities could signifcantly advance both highenergy and low-energy nuclear physics.Additionally,this approach has implications for the future electron-ion collider.While the possibilities are extensive,we focus on selected proposals that could beneft both the high-energy and low-energy nuclear physics communities.Originally prepared as input for the long-range plan of U.S.nuclear physics,this white paper refects the status as of September 2022,with a brief update on developments since then.

Optimization of performance of the KM2A full array using the Crab Nebula

The full array of the Large High Altitude Air Shower Observatory(LHAASO)has been in operation since July 2021.For its kilometer-square array(KM2A),we optimized the selection criteria for very high and ultrahigh energyγ-rays using data collected from August 2021 to August 2022,resulting in an improvement in significance of the detection in the Crab Nebula of approximately 15%,compared with that of previous cuts.With the implementation of these new selection criteria,the angular resolution was also significantly improved by approximately 10%at tens of TeV.Other aspects of the full KM2A array performance,such as the pointing error,were also calibrated using the Crab Nebula.The resulting energy spectrum of the Crab Nebula in the energy range of 10-1000 TeV are well fitted by a log-parabola model,which is consistent with the previous results from LHAASO and other experiments.

Evidence for particle acceleration approaching PeV energies in the W51 complex

Theγ-ray emission from the W51 complex is widely acknowledged to be attributed to the interaction between the cosmic rays(CRs)accelerated by the shock of supernova remnant(SNR)W51C and the dense molecular clouds in the adjacent star-forming region,W51B.However,the maximum acceleration capability of W51C for CRs remains elusive.Based on observations conducted with the Large High Altitude Air Shower Observatory(LHAASO),we report a significant detection ofγrays emanating from the W51 complex,with energies from 2 to 200 TeV.The LHAASO measurements,for the first time,extend theγ-ray emission from the W51 complex beyond 100 TeV and reveal a significant spectrum bending at tens of TeV.By combining the"π^(0)-decay bump"featured data from Fermi-LAT,the broadbandγ-ray spectrum of the W51 region can be well-characterized by a simple pp-collision model.The observed spectral bending feature suggests an exponential cutoff at~400 TeV or a power-law break at~200 TeV in the CR proton spectrum,most likely providing the first evidence of SNRs serving as CR accelerators approaching the PeV regime.Additionally,two young star clusters within W51B could also be theoretically viable to produce the most energeticγrays observed by LHAASO.Our findings strongly support the presence of extreme CR accelerators within the W51 complex and provide new insights into the origin of Galactic CRs.

丰中子核^(63,65,67)Mn的在束γ谱学研究

利用放射性束68Fe轰击液氢靶引起的敲出反应,研究了极端丰中子核^(63,65,67)Mn的激发态,指认了它们的自旋宇称,建立了这三个原子核的能级纲图。纲图包含11/2^(-)、9/2^(-)和7/2^(-)三个激发态以及5/2^(-)_(g.s.)基态,它们由三条ΔI=1的γ跃迁连接。这种能级结构与K=5/2时强耦合转动带的特征一致。使用改进的LNPS有效相互作用(LNPSm)的大规模壳模型计算能很好地重现观测到的能级。计算表明,^(65,67)Mn的低位激发态都主要包含处于4p-4h的中子组态和1p-1h的质子组态。基于实验结果发现,在吸积中子星壳中,与质量数A=63相关的Urea中微子冷却效果比预期的要强很多,而A=65,67的冷却效果比预期的更弱。

Effective charge from lattice QCD

Using lattice configurations for quantum chromodynamics(QCD)generated with three domain-wall fermions at a physical pion mass,we obtain a parameter-free prediction of QCD’s renormalisation-group-invariant process-independent effective charge,α^(k2).Owing to the dynamical breaking of scale invariance,evident in the emergence of a gluon mass-scale,m0=0.43(1)GeV,this coupling saturates at infrared momenta:α^(0)/π=0.97(4).Amongst other things:α^(k2)is almost identical to the process-dependent(PD)effective charge defined via the Bjorken sum rule;and also that PD charge which,employed in the one-loop evolution equations,delivers agreement between pion parton distribution functions computed at the hadronic scale and experiment.The diversity of unifying roles played byα^(k^2)suggests that it is a strong candidate for that object which represents the interaction strength in QCD at any given momentum scale;and its properties support a conclusion that QCD is a mathematically well-defined quantum field theory in four dimensions.

Dynamics of strong and radiative decays of D_s-mesons in the hadrogenesis conjecture

The positive parity scalar D ＊ s0 （2317） and axial-vector D ＊ s1 （2460） charmed strange mesons are generated by coupled-channel dynamics through the s-wave scattering of Goldstone bosons off the pseudoscalar and vector D（D s ）-meson ground states.The specific masses of these states are obtained as a consequence of the attraction arising from the Weinberg-Tomozawa interaction in the chiral Lagrangian.Chiral corrections to order Q 2 χ are calculated and found to be small.The D ＊ s0 （2317） and D ＊ s1 （2460） mesons decay either strongly into the isospin-violating π 0 D s and π 0 D ？ s channels or electromagnetically.We show that the π 0-η and （K^ 0 D ^＋-K^ ＋ D^ 0 ） mixings act constructively to generate strong widths of the order of 140 keV and emphasize the sensitivity of this value to the KD component of the states.The one-loop contribution to the radiative decay amplitudes of scalar and axial-vector states is calculated using the electromagnetic Lagrangian to chiral order Q 2 χ .We show the importance of taking into account processes involving light vector mesons explicitly in the dynamics of electromagnetic decays.The radiative width are sensitive to both η D s and KD components,hence providing information complementary to the strong widths on the positive parity D s-meson structure.